Jasmonate activates PuMYC2 and decreases histone acetylation levels to inhibit the ester aroma catabolism in cold-stored Nanguo pears fruit

Nanguo pear (Pyrus ussuriensis) is characterized by an intense fruit aroma, which is primarily attributed to volatile ester compounds. It has a short storage period at room temperature, and cold storage is often used in production to extend the storage period of the fruit. However, it leads to a significant decline in volatile ester compounds, which diminishes the aroma and reduces the commercial appeal of the fruit. In this study, we found that methyl jasmonate (MeJA) treatment significantly increased ester aroma synthesis and upregulated the expression of PuMYC2, which codes for a transcription factor involved in the JA signaling pathway in cold-stored Nanguo pear furits. Additionally, we observed a decrease in the expression of PuCXE15, a key gene responsible for ester aroma catabolism in MeJA+Cold fruits compared with cold fruits. We further found that PuMYC2 directly binds to the promoter of PuCXE15 and suppresses its transcriptional activity. Furthermore, MeJA treatment reduced histone acetylation levels of PuCXE15 promoter that inhibited PuCXE15 transcription and increased ester volatile compound levels in cold-stored Nanguo pears. Altogether, this study revealed that MeJA inhibits aroma degradation in cold-stored Nanguo pears through transcription regulation and epigenetic mechanisms, thereby provides a foundational understanding for improvement of fruit aroma quality.